Central projections and motor nuclei of the facial, glossopharyngeal, and vagus nerves in the mormyrid fish Gnathonemus petersii.

Most of the information about the anatomy of the fish's cranial nerves was collected in the first two decades of this century. Experimental analysis of the VIIth, IXth, and Xth cranial nerves by modern tract tracing techniques started about 20 years ago. Several species have been investigated to date, including one species of Agnatha (Myxinoidea), two species of elasmobranchs, and species of some orders of Teleostei like Cyprinidae, Siluriformes, Perciformes, and Gadidae.

[Long ascending fibers in the dorsal column of a teleost fish: a disynaptic pathway connecting sense organs to cerebellum].

In spite of the generally accepted opinion that long ascending proprioceptive and tactile fibers do not occur in the spinal dorsal columns of teleost fish, it was demonstrated with degeneration and axonal transport tracing methods that such dorsal column fibers exist in the teleost fish Gnathonemus petersii. These fibers are in fact common spinal afferent fibers originating in spinal ganglion cells. They connect the peripheral sense organs with the lateral funicular nuclei (Fl2) in which the dorsal column fibers terminate, directly through the dorsal columns.

A well defined spinocerebellar system in the weakly electric teleost fish Gnathonemus petersii. A tracing and immuno-histochemical study.

Long ascending fiber systems were investigated in the spinal cord of a teleost fish, Gnathonemus petersii. Concomitant results of Fink-Heimer degeneration tracing as well as CaBP28K immunohistochemical labelling demonstrate the existence of a well defined direct pathway from the very lowest spinal level to the caudal lobe of the cerebellum. HRP retrograde labelling shows that this pathway originates in a cellular column located in the most ventral part of the lateral column next to the lateral extremity of the ventral horn.

Serotoninergic neurons in the mormyrid brain and their projection to the preelectromotor and primary electrosensory centers: immunohistochemical study.

Serotonin-containing neurons in the brain of the weak-electric fish Gnathonemus petersii (mormyridae, teleostei) were studied with the aid of immunohistochemical labeling. Study of the central serotoninergic innervation was focused on the structures subserving the command of the electric organ and the first central relay of the electrosensory system. In the midline raphe nuclei, serotoninergic neurons formed a column that stretched from the ventral caudal medulla to the dorsal midbrain, ending caudal to the cerebellar peduncle.

The use of Quetol 651 for the post-embedding immunohistochemical demonstration of gamma-aminobutyric acid on semithin sections.

Quetol 651 was used as an embedding medium for the demonstration of gamma aminobutyric acid (GABA) in semithin sections by the peroxidase-anti-peroxidase method. In order to demonstrate the immunoreactivity, the embedding medium was partially dissolved using absolute ethanol containing 0.8-1 M NaOH or KOH for 5-7 min.